"Bombing civilian areas and populations is contrary to international law. I will summon the Israeli ambassador to condemn this unacceptable act and demand an explanation," Foreign Minister Hadja Lahbib said on X.

Enabel said in a statement that Abdallah Nabhan, 33, along with his seven-year-old son, 65-year-old father, 35-year-old brother and six-year-old niece, were killed "after an Israeli airstrike in the eastern part of the city of Rafah".

The airstrike hit the family home where 25 people were sheltering, including people displaced by the Israeli military operation in Gaza, Enabel said.

It said that Nabhan, who had worked on a Belgian development project helping young people find jobs, and his family were on a list Israel had of people eligible to exit Gaza, but that they were killed before being granted permission to leave.

Enabel's chief, Jean Van Wetter, called their deaths "yet another flagrant violation by Israel of international humanitarian law".

The health ministry in Gaza, run by the Hamas militant group, says more than 34,000 people have died in the war being waged in the Palestinian territory, most of them women and children.

Israel is conducting airstrikes and ground operations there in retaliation for a Hamas attack on October 7 that killed around 1,170 people in Israel, according to an AFP tally of Israeli figures.

Belgium, which currently holds the EU presidency, is among the European countries most vocal in condemning Israel's operation as disproportionately deadly for Palestinian civilians.